题面 枚举每个数字是否能被删去,然后就是如何判定图是否存在.应该从按“度数”从大到小排序,从最大的顺次向其他点连边(先连“度数”小的可能会把一些可以和大“度数”点连接的点用掉).但是这个排序每连一次都要做一次,而$N<=500$的情况下$O(n^3log$ $n)$并不能过.但是发现度数最多只有$n$,所以可以桶排,水过=.= USACO官方题解说可以再套一个数据结构变成$O(n^2log$ $n)$,然而并不会做 #include<cstdio> #include<cstring…

题目描述 Farmer John's N cows (2 <= N <= 500) have joined the social network "MooBook". Each cow has one or more friends with whom they interact on MooBook. Just for fun, Farmer John makes a list of the number of friends for each of his cows,…

题目 [USACO14MAR]Counting Friends G 题解 这道题我们可以将 \((n+1)\) 个边依次去掉,然后分别判断去掉后是否能满足.注意到一点, \(n\) 个奶牛的朋友之和必定为偶数,所以去掉的那个数值的奇偶性必定与 \((n+1)\) 个数值之和的奇偶性相同. 接下来很明显的,尽量将朋友多的和朋友多的匹配,所以先从大到小排序,将第一个奶牛和后面的奶牛依次匹配,如果匹配结束,第一个奶牛还有剩余,则此情况必然不可能成立:否则匹配完之后再按照 \(O(n)\) 复杂度的归并…

在上篇,我了解了基数的基本概念,现在进入Linear Counting算法的学习. 理解颇浅,还请大神指点! http://blog.codinglabs.org/articles/algorithms-for-cardinality-estimation-part-ii.html 它的基本处理方法和上篇中用bitmap统计的方法类似,但是最后要用到一个公式: 说明:m为bitmap总位数,u为0的个数,最后的结果为n的一个估计,且为最大似然估计(MLE). 那么问题来了,最大似然估计是什么东东…

来之不易的2017第一发ac http://poj.org/problem?id=2386 Lake Counting Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 31474   Accepted: 15724 Description Due to recent rains, water has pooled in various places in Farmer John's field, which is repr…

ZOJ3944 People Counting ZOJ3939 The Lucky Week 1.PeopleConting 题意:照片上有很多个人,用矩阵里的字符表示.一个人如下: .O. /|\ (.) 占3*3格子,句号“.”为背景.没有两个人完全重合.有的人被挡住了一部分.问照片上有几个人. 题解: 先弄个常量把3*3人形存起来,然后6个部位依次找,比如现在找头,找到一个头,就把这个人删掉(找这个人的各个部位,如果在该部位位置的不是这个人的身体,就不删),删成句号,疯狂找就行了. 代码:…

#include <stdio.h> #include <malloc.h> #define MAX_STACK 10 ; // define the node of stack typedef struct node { int data; node *next; }*Snode; // define the stack typedef struct Stack{ Snode top; Snode bottom; }*NewStack; void creatStack(NewSt…

1004. Counting Leaves (30)   A family hierarchy is usually presented by a pedigree tree. Your job is to count those family members who have no child. Input Each input file contains one test case. Each case starts with a line containing 0 < N < 100,…

Problem Figure 2. The Hamming distance between these two strings is 7. Mismatched symbols are colored red. Given two strings ss and tt of equal length, the Hamming distance between ss and tt, denoted dH(s,t)dH(s,t), is the number of corresponding sym…

Problem A string is simply an ordered collection of symbols selected from some alphabet and formed into a word; the length of a string is the number of symbols that it contains. An example of a length 21 DNA string (whose alphabet contains the symbol…